2-Way Directional Valve (IL)
Two-line flow control valve in an isothermal liquid network.
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Description
The 2-Way Directional Valve (IL) block represents a two-line valve, such as a shut-off valve. Use this block to model a flow reducing control element that responds to pressure in another part of the system. The block uses a variable orifice to control flow between ports A and B. The S signal determines the movement of the spool to open or close the valve.
You can parameterise the valve opening linearly or with tabular data.
Linear parameterization
If `Linear - Area vs. spool travel' is selected for the Orifice parameterization, the opening area is a linear function of the spool travel distance.
,
where
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- is the area of the open port.
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- is the distance of the spool valve movement at the port inlet S. .
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- value of the spool travelling parameter between closed and open orifice (value of Spool travelling between closed and open orifice).
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- value of the leakage area parameter (value of the Leakage area parameter).
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- parameter value of the maximum orifice area (parameter value Maximum orifice area).
Note the linear scaling from to in the figure:
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When the valve is in the nearly open or nearly closed position in the linear parameterization, you can maintain the numerical stability of the simulation by adjusting the smoothing factor, the value of the Smoothing factor parameter. If the value of Smoothing factor is not zero, the block smoothly saturates the opening region between and .
Tabular parameterization
If Tabulated data - Area vs. spool travel is selected for Orifice parameterization, the block uses the Spool travel vector and the valve area vector parameters to determine the relationship between and by interpolation. and are the first and last parameters of the valve area vector parameter respectively.
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If Tabulated data - Volumetric flow rate vs. spool travel and pressure drop is selected for Orifice parameterization, the block uses the volumetric flow rate table Volumetric flow rate table, q(ds,dp), the free fall vector Pressure drop vector, dp and the spool travel vector Spool travel vector, ds to determine the volumetric flow rate, .
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Ports
Input
S - valve spool movement
scalar
Input port of the valve spool movement that sets the valve opening. A positive value causes the valve to open.
Non-directional
A - isothermal liquid port
isothermal liquid
isothermal liquid port, corresponds to the inlet or outlet of the valve. This block has no internal directionality.
B - isothermal liquid port
isothermal liquid
isothermal liquid port, corresponds to the inlet or outlet of the valve. This block has no internal directionality.
Parameters
Orifice parameterization - method for calculating the valve area
Linear - area vs. spool travel (by default) | Tabulated data - Area vs. spool travel | Tabulated data - Volumetric flow rate vs. spool travel and pressure drop
Method for calculating valve area in modelling.
Spool position at maximum orifice area - spool position at maximum orifice area
5e-3 m (by default) | positive scalar
Position of the spool moving element when the valve is fully open.
By default value represents a system with zero overlap. A positive non-zero value represents a partially overlapped or partially closed system. A negative non-zero value represents an overlapped system where the valve remains open over the travel range.
Spool travel between closed and open orifice - maximum spool travel
5e-3 m (by default) | Positive scalar
Spool travel in the zone of maximum valve opening.
Dependencies
To use this parameter, set the Orifice parameterization parameter to Linear - area vs. spool travel.
Maximum orifice area - maximum valve opening area
1e-4 m² (by default) | positive scalar.
Maximum valve area during the simulation.
Dependencies
To use this parameter, set the Orifice parameterization parameter to Linear - area vs. spool travel.
Leakage area - area of valve clearance in fully closed position
1e-10 m² (by default) | positive scalar.
The sum of all clearances when the valve is in the fully closed position. Any area less than this value is maintained at the specified leakage area. This parameter contributes to the stability of the numerical solution by maintaining flow continuity.
Dependencies
To use this parameter, set the Orifice parameterization parameter to `Linear - area vs. spool travel'.
Spool travel vector - spool position vector
[0, 0.002, 0.004, 0.007, 0.017] m (by default) | `vector'.
Spool position vector. The one-to-one spool position vector corresponds to the Orifice area vector. A positive value corresponds to an open valve. The values are listed in ascending order and the first element must be 0. Linear interpolation is used between the data points in the table.
Dependencies
To use this parameter, set the Orifice parameterization parameter to `Tabulated data - Area vs. spool travel'.
Orifice area vector - vector of valve opening area values
[1e-09, 2.0352e-07, 4.0736e-05, 0.00011438, 0.00034356] m² (By default) | ` vector'.
Vector of valve area values for the tabular parameterization of the valve area. The values in this vector are related one-to-one with the elements in the Spool travel vector. If the vector is incremented, the first element of this vector is the valve leakage area and the last element is the maximum valve area. Linear interpolation is used between data points.
Dependencies
To use this parameter, set the Orifice parameterization parameter to `Tabulated data - Area vs. spool travel'.
Spool travel vector, ds - spool position vector
[0, 0.002, 0.004, 0.007, 0.017] m (by default) | ` vector'.
Spool position vector for tabular parameterization of the volumetric flow rate. The spool position vector corresponds one-to-one to the pressure drop vector Pressure drop vector, dp, for the two-dimensional dependence of the volumetric flow rate table Volumetric flow rate table, q(ds,dp). A positive value corresponds to the valve opening. The values are listed in ascending order and the first element must be 0. Linear interpolation is used to calculate intermediate values.
Dependencies
To use this parameter, set the Orifice parameterization parameter to Tabulated data -Volumetric flow rate vs. spool travel and pressure drop.
Pressure drop vector - vector of pressure drop values
[0.3, 0.5, 0.7] MPa (by default) | ` vector`.
Vector of differential pressure values for the volume flow rate. The one-to-one differential pressure vector corresponds to the spool position vector Spool travel vector, ds for the two-dimensional relationship of the volumetric flow rate table Volumetric flow rate table, q(ds,dp). The values are listed in ascending order and must be greater than 0. Linear interpolation is used to calculate intermediate values.
Dependencies
To use this parameter, set the Orifice parameterization parameter to Tabulated data -Volumetric flow rate vs. spool travel and pressure drop.
Volumetric flow rate table, q(ds,dp) - volumetric flow rate table
1e-3 * [1.7e-05 2e-05 2.6e-05; 0.0035 0.0045 0.0053; 0.7 0.9 1.06; 1.96 2.5 3; 6 7.7 9.13] m³/s (By default)` | matrix m to n
Matrix of m by n volume flow rates based on independent values of pressure drop and spool position. m and n are the dimensions of the corresponding vectors:
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m - number of elements in the Pressure drop vector, dp.
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n - number of elements in the spool position vector Spool travel vector, ds.
Dependencies
To use this parameter, set the Orifice parameterization parameter to Tabulated data - Volumetric flow rate vs. spool travel and pressure drop.
Discharge coefficient - flow coefficient
0.64 (by default) | positive scalar in the range [0,1].
Correction factor that takes into account discharge losses in theoretical flows.
Dependencies
To use this parameter, set Orifice parameterization to `Linear - area vs. spool travel' or `Tabulated data - Area vs. spool travel'.
Critical Reynolds number - upper limit of Reynolds number for laminar flow
150 (By default) | `positive scalar'.
Upper limit of Reynolds number for laminar flow through the orifice.
Dependencies
To use this parameter, set the Orifice parameterization parameter to `Linear - area vs. spool travel' or `Tabulated data - Area vs. spool travel'.
Smoothing factor - numerical smoothing factor
0.01 (by default) | positive scalar in the range [0,1].
A continuous smoothing factor that introduces a gradual change level based on the flow characteristic when the valve is in the nearly open and nearly closed positions. Set a non-zero value less than one to increase the stability of the simulation in these modes.
Dependencies
To use this parameter, set the Orifice parameterization parameter to `Linear - area vs. spool travel'.
Pressure recovery - whether to take into account the pressure rise when the area expands
off (By default) | `on
Whether to take into account the pressure rise when fluid flows from a smaller cross-sectional area to a larger cross-sectional area.
If Pressure recovery is unchecked, this pressure increase is not taken into account.
Cross-sectional area at ports A and B - area at the inlet or outlet of the valve
Inf (By default) | positive scalar
The cross-sectional area at the inlet and outlet ports A and B. This area is used in the pressure flow velocity equation that determines the mass flow rate through the orifice.
Dependencies
To use this parameter, set Orifice parameterization to `Linear - area vs. spool travel' or `Tabulated data - Area vs. spool travel'.